Process of making propellent powder



RICHARD GEORGE WOODBRIDGE, JR., OF. WILMINGTON, DELAWARE, ASSIGNOR TO E. I. DU FONT DE NEMOURS 6: COMPANY RATION or DELAWARE.

,' OF WILMINGTON, DELAWARE, A CORPO- PROGESS OF MAKING PBOPELLENT POWDER.

No Drawing.

To allwhom it may concern:

Be it known that I, RICHARD GEORGE WOODBRIDGE, Jr., a citizen of the United States, and a resident of Wilmington, in the county of New Castle and State of "Delaware, have invented a certain new and useful Process of Making Propellent Powder, of which the following is a specification.

to the various kinds of rifle and cannon pow ders. e i

The object of my invention is to provide a process of producing powders of this type which do not have the disadvantage of previous procemes of producing powders containing coatings on the outside thereofbut not impregnatlng the surface of the same,

that is to say, the great difficulty of ignition which often resulted in hang fires.

Another object of my invention is to provide a process by which a powder is obtained which will produce considerably less Erosion in rifle linings than previous powers.

A further object is to provide a process by means of which the surface of the powder grains may be effectively impregnated with a deterrent material which is not an explosive in such a manner that the grains are prevented from adhering to one another,

I as well as to secure more uniform impregnation of the grain by the coating materials than hitherto.

The deterrent materials which may be used in my process are particularly the dialkyldiarylureas, such as dimethyldiphenylurea, CO (N ((1H,) 0 H, 2 diethyldiphenylurea, CO (N C 11 C H 2 methylethyldiphenylurea, N (CH,) (O H )CO.N(C,H C 11 etc., these ureas having in general a solvent or colloiding action on nitrocellulose and the property of penetrating and inrpregnating the powder grain when heated with the latter in the presence of water to a temperature of not more than 100 C.

One object of my invention is especially to provide a process by means of which a Specification of Letters Patent.

Patented May 24, 1921.

Application filed August 8, '1919. Serial No. 316,030.

deterrent material such as dimethyldiphe- 'nylurea that is not explosive, which, because of its low volatility and good stability, as well as other properties would be suitable for surface impregnation of the smokeless powder grains, but which has such. a high melting point that it could not be used in a melted condition to impregnate the surface of the powder grains because such high temperature would affect the stability of the powder, can be used because of the fact that it can be applied at even lower temperatures than its melting point, with the aid of hot water, as the presence of the water causes it to melt below the temperatures at which it would otherwise meltr The object of my invention is furthermore to provide a process which is an impreve ment over the process as set forth in the ap lication of Alfred L. Broadbent and mysel upon the process of making propellent powder, Serial No. 109,249, filed July 14,

Further objects of my invention will appear from the detailed description thereof contained hereinafter.

While my invention is capable of embodiment in many different forms, for the purpose of illustration I shall describe only certain ways of carrying out my invention hereinafter.

For example, 100 parts by weight of nitrocellulose powder grains are introduced into a revolving mixing drum of any desired character, which may or may not be provided with longitudinally directed ribs on the interior cylindrical surface. Thereafter, I introduce into the drum 3 parts by weight of dimethyldiphenylurea, after which the entire mass is covered with water. The dimethyldiphenylurea' may be practically pure, havin a meltin point between 120 and 121 but pre erably I use a commercial 'dimethyldiphenylurea containing some impurities, and melting at 110 C., or over. After the materials in the drum have been thoroughly mixed, that is to say in from five to ten minutes, heat is applied in any suitable manner as by injecting steam into the drum or into a jacket thereon, while the temperature is gradually raised'to between 80 C. and-100 'C., and preferably to between 85 and 909 C. This will be sufficient in the presence of the water to melt four hours.

tionary tank of hot water at a temperature 7 between 80 and 100 C. and preferably be-,

tween 85 and 90 C., where they remain for a period amounting approximately to twenty- After this the powder grains are removed and dried. The impregnation is completed in this manner and at the temperature referred to notwithstanding thefact that the dimethyldiphenylurea of the grade used might melt for example at 115 C.

A nitrocellulose powder before having been impregnated as above, will givein a military rifle a muzzle velocity of 2,7 00- feet per second and a mean pressure of 49,000 pounds per square inch, with a charge weighing forty-five grains, while a sample of the powder impregnated as above, will give the same muzzle velocity with a mean pressure of only 40,000 to 42,000 pounds per square inch, with a charge weighing 4748 grains. The difference in the erosive effect of the two powders is even more marked, as the erosion by the impregnated powder 1s only one-fourth to one-third that of the powder which has not been impregnated.

The proportions in the above mixture may be varied through wide limits. For example, three parts by weight of dimethyldiphenylurea may be used, but any amount varying from one to ten parts by weight may be used according to the ballistic re- ,sult desired.

When the deterrent material employed is diethyldiphenylurea, which has a melting oint of 79 (3., the temperature of the water 1n the above described process is maintained between 65 and C. In the case of methylethyldiphenylurea, with a melting point of 5758- (3., the water is maintained at a temperature between 50 and 60 C. In other respects the conditions of operation are about the same.

While I have described my invention above in detail, I wish it to be understood that many changes may be made therein without departing'from the spirit of the invention.

I claim 1. The process which comprises impregmating the surface of an explosive grain insoluble 1n water with a deterrent material,

raraore "to treatment with hot water.

The process which comprises impregnating the surface of an explosive grain insoluble in water with a deterrent material comprising essentially dimethyldiphenylurea, all of the deterrent material used being substantially insoluble in water, and having a melting point above 100 (3., by subjecting the grain, while intimately mixed with said deterrent material, to treatment with hot water.

4. The process which comprises impregnating the surface of an explosive grain insoluble in water with dimethyldiphenylurea as the sole deterrent, by subjecting the grain, while intimately mixed with said dimethyldiphenylurea, to treatment with hot water.

5. The process which comprises impregnating the surface of an explosive grain insoluble in water with a deterrent material, all of the deterrent material used having a melting point above 100 C. and being substantially insoluble in water, by subjecting the grain, while intimately mixed with saidwater, by subjecting the grain, 'while intimately mixed with said deterrent material,

to treatment with hot water, at a temperature below the melting point of the deterrent material.

7. The process which comprises impregnating the surface of an explosive grain insoluble in water with a deterrent material comprising essentially dimethyldiphenylurea, all of the deterrent material used being substantially insoluble in water, and having a melting point above 100 C., by subjecting the grain, while intimately mixed with said deterrent material, to treatment with hot water, at a temperature below the melting point of the deterrent material.

8. The process which comprises impregnating the surface of an explosive grain insoluble in water with dimethyldiphenylurea as the sole deterrent, by subjecting the grain while intimately mixed with said dimethyldiphenylurea, to treatment with hot water, at a temperature below the melting point of the dimethyldiphenylurea.

9. The process which comprises impregnating the surface of a nitrocellulose powder grain insolublein water with a deterrent material, all of the deterrent material used having a melting point above 100 (J. and being substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent material, to treatment with hot water, at a temperature below the melting point of the deterrent material.

10. The process which comprises impregnating the surface of a nitrocellulose powder grain insoluble in water with a deterrent material, all of the deterrent material used being not explosive and substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent material, to treatment with hot water, at a temperature below the melting point of the deterrent material.

11. The process which comprises impregnating the surface of a nitrocellulose powder grain insoluble in water with dimethyl- (liphenylurea as the sole deterrent by subjecting the grain, while intimately mixed with said dimethyldiphenylurea, to treatment with hot water, at a temperature below the melting point of the dimethyldiphenylurea. Y

12. The process of treating nitrocellulose powder grains which consists in treating with hot water said grains intimately mixed with a dialkyldiarylurea having a colloiding actionon said grains and capable of impregnating said grains in the presence of water maintained at a temperature of less than 100%.

13. The process oftreating nitrocellulose deterrent material composed of a dialkyldiarylurea to the action 'of a hotliquid which is chemically inert with respect to said grains and said deterrent material, and

in which said grains and said deterrent material are insoluble.

15. The process of treating nitrocellulose powder grains which comprises subjecting said grains while intimately mixed with a deterrent material, all of the material used being not explosive, t0 the action of a hot liquid which is chemically inert with respect to said grains and said deterrent material, and in which said grains and said deterrent material are insoluble.

16. The process of treating nitrocellulose powder grains which consists in subjecting said grains while intimately mixed with dimethyldiphenylurea to the action, at a temperature between 80 and 100 (3., of a liquid which is chemically inert with respect to said grains and said dimethyldiphenylurea, and in which said grains and said d-imethyldiphenylurea are insoluble.

17. The process of treating nitrocellulose powder grains which consists in subjecting said grains while intimately mixed with a deterrent material composed of a dialkyldiarylurea to the action, at a temperature below 100 0., of a liquid which is chemically inert with respect tosaid grains and said deterrent material, and in which said grains and said deterrent material are insoluble.

In testimony whereof I afiix my signature.

RICHARD GEORGE WOODBRIDGE, Jr. 

